Radio module, method to operate a radio module, radio terminal, method to operate a radio terminal

ABSTRACT

A radio module (RM) for a radio terminal (T) is provided, wherein the radio module (RM) comprises: a transmitter (Tx) configured to transmit within a time period data either on a first radio channel (RCH1) of a first radio communications network according to a first operating mode or on a second radio channel (RCH2) of a second radio communications network according to a second operating mode; and a controller (CTRL) being configured to schedule a selection of one of the operating modes of the transmitter (Tx), wherein the selection comprises switching of at least one parameter of the transmitter (Tx) according to the selected operating mode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/077,045 filed Oct. 22, 2020, which claims priority to European PatentApplication No. 19204855.1, filed Oct. 23, 2019, the entire contents ofwhich are incorporated by reference herein.

BACKGROUND OF THE INVENTION

The invention is directed to a radio module, a method to operate a radiomodule, a radio terminal, and a method to operate a radio terminal.

To provide multi-connectivity for a radio terminal, the radio terminalhas a plurality of radio modules configured to operate in a specificradio communications network.

SUMMARY OF THE INVENTION

A first aspect is directed to a radio module for a radio terminal,wherein the radio module comprises: a transmitter configured to transmitwithin a time period data either on a first radio channel of a firstradio communications network according to a first operating mode or on asecond radio channel of a second radio communications network accordingto a second operating mode; and a controller being configured toschedule a selection of one of the operating modes of the transmitter,wherein the selection comprises switching of at least one parameter ofthe transmitter according to the selected operating mode.

Advantageously, the complexity of the transmitter is reduced as only oneradio channel of one radio communication system can be selected at thesame time instant. Therefore, only one entity for encoding andup-sampling has to be integrated into the transmitter, which reduces thecosts of the transmitter. On the other hand, the radio module providesmulti-connectivity in a time-division-multiplexed manner. The benefitsof using multiple paths comprise an increase in reliability.

To increase the reliability appropriate multi-connectivity methods, forexample packet duplication, are deployed based on the characteristics ofthe communication paths, e.g. the received signal strength.

Consequently, the radio module provides an increase in reliability byenabling the potential of multi-connectivity without the need for asecond radio module that will increase in the bill of materials of thefinal product.

An advantageous example is characterized by that the transmitter isconfigured to encapsulate a received first type MAC PDU into a firsttype PHY PDU, to map the first type PHY PDU to be transmitted on atleast one first subcarrier and to subsequently up-convert to a firstradio frequency higher than the at least one first subcarrier; and bythat the transmitter is configured to encapsulate a received second typeMAC PDU into a second type PHY PDU, to map the second type PHY PDU to betransmitted on at least one second subcarrier and to subsequentlyup-convert to a second radio frequency higher than the at least onesecond subcarrier.

Therefore, the transmitter provides an advantageous interface, which canbe fed by different communication stacks. Especially, the communicationsstacks providing the MAC PDUs can be provided as software.

The first subcarrier and the first radio frequency represent parametersof the transmitter according to the first operating mode. The secondsubcarrier and the second radio frequency represent parameters of thetransmitter according to the second operating mode.

An advantageous example is characterized by that the controller isconfigured to switch the at least one parameter according to the firstor second radio channel in dependence on a pre-determined switchingpattern which comprises fixed access periods for the transmitter.

By providing a pre-determined switching pattern, the transmission ratiofor both radio communication networks is provided.

An advantageous example is characterized by that the controller isconfigured to switch the at least one parameter according to the firstor second radio channel in dependence on a received end of transmissionindicator, which indicates an end of a transmission via the second orfirst radio channel.

Advantageously, the controller gives access to the transmitter for aradio transmission if the other radio channel is not used by the radiomodule.

An advantageous example is characterized by that the radio modulecomprises: a receiver being configured to receive at least one grant,which grants the transmitter to transmit data via the first or secondradio channel; and the controller being configured to switch to thefirst or second operating mode in dependence on the received grant

Advantageously, if the first and/or second radio communications systemhas a granting procedure for example operated via an access point, thereceived grant result in the controller switching the operating mode tothe radio channel for which the grant was received.

An advantageous example is characterized by that the radio modulecomprises: the controller being configured to operate the transmitter totransmit a first scheduling request during the first operating modetowards a scheduling entity of the first radio communications network.

Advantageously, the controller triggers the grants and adapts thescheduling of the selection of the operating modes according to thereceived grants. Therefore, the radio module provides a synchronizationtechnique for the first radio communications network.

An advantageous example is characterized by that the radio modulecomprises: the controller being configured to operate the transmitter totransmit a second scheduling request during the second operating modetowards a scheduling entity of the second radio communications network.

Advantageously, the controller adapts the operation of the transmitterin dependence on scheduling grants originating from at least twodifferent radio communication networks. The scheduling requests aredetermined by the controller in order to trigger grants that point togranted radio resources that do not interfere in time.

An advantageous example is characterized by that the radio modulecomprises: the controller being configured to remain with the presentoperating mode or switch to the first or second operating mode independence on a transmission priority of data.

By incorporating the transmission priority into the decision forscheduling the selection of the operating mode, other influencingparameters can be overridden. Advantageously, this guaranteestransmission of certain high priority marked data.

An advantageous example is characterized by that the radio modulecomprises: a/the receiver being configured to sense the first radiochannel as free or busy; the controller being configured to switch thetransmitter from the first operating mode to the second operating mode,if the first radio channel is sensed free, and to switch the transmitterfrom the second operating mode to the first operating mode, if the firstradio channel is sensed busy.

Therefore, a mode priority is provided, wherein the transmission via thefirst radio channel is preferred over the transmission via the secondradio channel. Only if the first radio channel is sensed free, data istransmitted via the second radio channel.

A second aspect of the description is directed to a method to operate aradio module, wherein the method comprises: transmit within a timeperiod data either on a first radio channel of a first radiocommunications network according to a first operating mode or on asecond radio channel of a second radio communications network accordingto a second operating mode; and schedule a selection of one of theoperating modes of the transmitter, wherein the selection comprisesswitching of at least one parameter of the transmitter according to theselected operating mode.

A third aspect is directed to a radio terminal for at least two radiocommunication networks, wherein the radio terminal comprises the radiomodule according to the first aspect.

An advantageous example is characterized by that the radio terminalcomprises at least one processor, at least one memory with computerprogram code, and at least one antenna, the computer program code beingconfigured to interact with the at least one processor, the at least oneantenna, and the at least one radio module to cause the radio terminalto determine a/the first type MAC PDU in dependence on a first payloadand provide the first type MAC PDU to the transmitter; and determinea/the second type MAC PDU in dependence on a second payload and providethe second type MAC PDU to the transmitter.

Therefore, an advantageous interface is provided allowing a plurality ofsoftware stacks for determining and providing MAC PDUs to thetransmitter.

A fourth aspect is directed to a method to operate the radio terminalaccording to the third aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a radio module of a radio terminal;

FIG. 2 schematically depicts an example of the radio terminal; and

FIGS. 3 to 6 each schematically depict a sequence diagram.

DETAILED DESCRIPTION

FIG. 1 schematically depicts a radio module RM of a radio terminal T.The radio module RM is adapted to transmit on a plurality of radiochannels RCH1, RCH2 of different radio communication networks. In theexample shown, a first network entity N1 communicates with the radioterminal T via the first radio channel RCH1. A second network entity N2communicates with the radio terminal via the second radio channel RCH2.Both radio channels RCH1 and RCH2 belong to different radiocommunication networks and differ at least in a radio frequency, andfurther in at least one of the following: a modulation scheme, a codingscheme, a subcarrier frequency, and a transmission time interval.

The access to the radio channels RCH1 and RCH2 is handled in adistributed or centrally managed manner. Therefore, examples of a systemcomprises network entities N1, N2 with the same or different mediumaccess schemes.

The radio module RM comprises a transmitter Tx and a controller CTRL.The transmitter Tx is configured to transmit within a time periodprovided data either on a first radio channel RCH1 of a first radiocommunications network according to a first operating mode or on asecond radio channel RCH2 of a second radio communications networkaccording to a second operating mode. The provided data is mapped to asubcarrier, subsequently up-converted to a corresponding radio signaland provided by the transmitter Tx to at least one antenna A in order tobe transmitted via a radio signal of the first or second radio channelRCH1, RCH2.

The data to be transmitted is provided to the transmitter Tx. Forexample, MAC layer tasks and higher layer tasks are processed insoftware. Therefore, the data to be transmitted is handed over to thetransmitter Tx at an egress section of the MAC layer.

The controller CTRL is configured to schedule a selection of one of theoperating modes of the transmitter Tx, wherein the selection comprisesswitching of at least one parameter of the transmitter Tx according tothe selected operating mode.

The at least one parameter of the transmitter Tx for operating the radiochannels RCH1 and RCH2 of the respective radio communication systemcomprises one of the following:

a modulation scheme,

a coding scheme,

a radio frequency,

a subcarrier frequency,

a transmission time interval.

The selection of one of the operating modes comprises a switch operationthat comprises the adaption of the at least one parameter of thetransmitter Tx. This selection is associated with a switching delay.

Examples for the scheduling of the selection comprise:

a fixed timing schedule exemplified in FIG. 3,

a flexible timing schedule based on transmission need of the associatedcommunication stack exemplified in FIG. 4

a flexible timing schedule based on external radio access schedulingexemplified in FIG. 5;

a flexible timing schedule based on transmission priorities exemplifiedin FIG. 5; and

a flexible timing schedule based on channel sensing exemplified in FIG.6.

Of course, the provided scheduling method of the selection of theoperating mode can be changed during the operation of the radio moduleRM. In addition, a combination of the provided methods is possible.

The resources of the transmitter Tx, i.e. the RF chain and the basebandprocessing, are divided in time slots and the controller CTRL schedulesthe access to these resources between two or more independentcommunication protocol stacks. The physical layer resources areconfigured via the at least one parameter independently for each timeslot, wherein each time slot is therefore bound to one of the operatingmodes. The provided access scheme for the transmitter Tx increases thedelay of the transmission over the multiple paths to a certain degreedue to the time-multiplexed use of the resources of the transmitter Tx.

The transmitter Tx is connected to the at least one antenna A in orderto transmit the radio signal. According to the provided access schemefor the radio module RM the radio signal switches the radio frequenciesin a time-division manner. Therefore, the radio signals transmitted bythe radio module have different frequencies and are independent of eachother, i.e. for example, different source addresses are used.

By adjusting the length and the beginning of the time slots, the accessscheme is optimized to various conditions in different bands. E.g.exclusive access to spectrum with a central coordination unit like inIMT-spectrum or in the 3.7-3.8 GHz band or shared access to spectrumwith a distributed coordination based on CSMA-CA as in the 2.4 and 5 GHzbands. In this example, the terminal T is connected to two access pointsin form of the network entities N1 and N2 that are working at 5 GHz and3.7 GHz, respectively.

FIG. 2 schematically depicts an example of the radio terminal T. Theradio terminal T comprises the radio module RM and a processor P. Amemory M with a computer program code is provided. If executed on theprocessor P the computer program code causes the radio terminal T toexecute an application APP, a first communication stack St1, and asecond communication stack St2. The application APP provides a pluralityof queues qx with data to be transmitted via at least one of the radiochannels RCH1, RCH2.

In the shown example, the radio terminal T comprises a receiver Rxconnected to the at least one antenna A. The receiver Rx is configuredto sense an occupation of at least one of the radio channels RCH1 andRCH2 and/or is configured to provide data, which is transmitted via atleast one of the radio channels RCH1 and RCH2 to the controller CTRL.The receiver Rx as an occupation sensing device may comprise a lesscomplex receiver chain which does not completely decode the receiveddata but only senses occupation.

In another example, the receiver Rx configured to receive within a timeperiod data either on the first radio channel RCH1 of the first radiocommunications network according to the first operating mode or on thesecond radio channel RCH2 of the second radio communications networkaccording to the second operating mode. The operating modes are switchedvia the switching signal sw. According to this example, both thetransmitter Tx and the receiver Rx are bound to the currently set radiofrequency. Advantageously, only one radio module is needed, as only theradio frequency on which the receiver RX is currently listening is used.If the respective radio channel RCH1, RCH2 is occupied, then the radioterminal T switches to the other radio channel RCH2, RCH1 and tries totransmit there. In the case of two radio networks, the receiver Rxswitches back and forth between frequencies, standards, etc. to receivedata and set a sleep time for the other radio network, wherein thereceiver Rx does not receive. During this sleep time the other networkentities temporarily store packets for the receiver Rx until thereceiver Rx returns to receive on the respective frequency.

In the shown example, the controller CTRL is provided like thetransmitter Tx as hardware. In an alternative example, the controllerCTRL is provided as a software function that is provided as computerprogram code that is run on a dedicated processor or on the processor P,wherein the transmitter Tx is realized as hardware.

The first communication stack St1 receives at its ingress queue iq1 afirst payload p1 from the application APP. A protocol processing unitpp1 takes the first payload p1 from the ingress queue iq1, processes thepayload p1 according to the assigned at least one first communicationprotocol and determines a corresponding first type MAC PDU (1) that isprovided in an egress queue eq1.

The transmitter Tx comprises a PHY unit 200 that is configured toencapsulate the first type MAC PDU (1) into a first type PHY PDU (1).The first type PHY PDU (1) enters a queue 202. A radio unit 204 maps thefirst type PHY PDU (1) to be transmitted on at least one firstsubcarrier and to subsequently up-convert to a first radio frequencyhigher than the at least one first subcarrier.

According to an example, the radio unit 204 implements at least twodifferent radio standards in the PHY and switches between these radiostandards in dependence on the switching signal sw, thereforemaintaining the time multiplex between the two radio systems.

According to a further example, the radio unit 204 implements at leasttwo similar radio standards in the PHY interface and switches betweenthese similar radio standards in dependence on the switching signal sw,wherein the difference between the two similar radio standards relies inthe radio frequencies and subcarrier frequencies.

The second communication stack St2 receives at its ingress queue iq2 asecond payload p2 from the application APP. A protocol processing unitpp2 takes the second payload p2 from the ingress queue iq2, processesthe payload p2 according to the assigned at least one secondcommunication protocol and determines a corresponding second type MACPDU (2) that is provided in an egress queue eq2.

The PHY unit 200 is configured to encapsulate the second type MAC PDU(2) into a second type PHY PDU (2). The second type PHY PDU (2) entersthe queue 202. The radio unit 204 maps the second type PHY PDU (2) to betransmitted on at least one second subcarrier and subsequentlyup-converts to a second radio frequency higher than the at least onesecond subcarrier.

The controller CTRL schedules the access to the transmitter Tx for theat least two communication stacks St1 and St2. A scheduling decision ofthe control CTRL involves transmitting a switching signals sw to thetransmitter Tx. In an example, the radio unit 204 receives the switchingsignal sw. After the reception of the switching signal 204, the radiounit 204 transmits the PHY PDUs residing in the queue 202 in order toempty the queue 202. Then the radio unit 204 changes the at least oneparameter in order to change the operating mode of the transmitter Tx.In other words, the radio unit 204 changes its transmission mode inorder to transmit the radio signal via the radio channel RCH1, RCH2 thatwas not selected before the switching signal sw was received. When theradio unit 204 has changed its operating mode successfully, the radiounit 204 transmits a further switch signal sw2 to the PHY unit 200 inorder to switch to the selected operating mode. In other words, afterreceiving the further switch signal sw2 the PHY unit 200 will switch toreceive MAC PDUs from the other one of the egress queues eq2, eq1 of therespective communication stack St2, St1.

Therefore, the controller CTRL controls at least the radio frequencysetting of the radio unit 204 and issues the switching signal sw tochange from the first radio frequency to the second radio frequency.This switching signal sw can be triggered based on a specific switchingperiod, the end of the transmission of the communication stack that istransmitting at the current radio frequency or based on other inputssuch as scheduling grants from an external central coordinator such as abase station or access point. Before issuing the switching signal sw,the currently operating communication stack St1 is informed about theupcoming switch in frequency such that it can either pause itsprocessing, run a timer related to scheduling or medium access such asbackoff procedures in CMSA/CA. In another example, the communicationstack St1 or the controller CTRL monitors the priority of incomingpayload p1 for the communication stack St1 and request access to thetransmitter Tx.

After a switching period that is required by the RF hardware of theradio module 204 to set a new radio frequency, the activatedcommunication stack St1, St2 continues with a paused transmissionprocess of data until the controller CTRL signals the next switch viathe switching signal sw.

In a setup where the application APP demands strict quality of servicerequirements, the controller CTRL will use these requirements (e.g.latency deadline) as an input and adapt the switching between the radiosystems accordingly. If both radio communication networks are managed ina distributed manner and e.g. use the IEEE 802.11 DCF as input, thebackoff-value of both radio communication networks is used to determinevia the controller CTRL the most promising switching routine to fulfillthe quality of service requirements. In situations where the first radiocommunications network provides a much higher backoff than the secondradio communications network, the controller CTRL allocates the nexttime slots for transmission via the first radio communications networkand let the second communication stack St2 count down its backoff value,while the first communication stack St2 uses the time slots to transmitvia the transmitter Tx.

FIG. 3 schematically depicts a sequence diagram of a method to operatethe terminal T.

The controller CTRL is configured to switch the at least one parameteraccording to the first or second radio channel RCH1, RCH2 in dependenceon a pre-determined switching pattern which comprises fixed accessperiods aP for the transmitter Tx.

According to a step 302, the application APP determines payloads p1 andp2 and submits these to the corresponding communication stacks St1, St2.At the time t0_3 the second communication stack St2 starts accessing thetransmitter Tx during the access period aP(2). During the access periodaP(2), the second communication stack St2 has access to the transmitterTx. During the access period aP(2) the controller CTRL schedules via astep 304 the selection of the operating mode OP of the transmitter Tx.Step 304 comprises that the first communication stack St1 is informedthat it has access starting at time t2_3 to use the transmitter Tx. Step304 comprises that the second communication stack St2 has to end itsaccess to the transmitter Tx at time t1_3.

During the switching period swP the controller CTRL determines in a step306 the switching signal sw. According to a step 308, upon receiving theswitching signal sw the transmitter Tx changes its present secondoperating mode to the first operating mode in order to use the firstradio channel instead of the second radio channel.

During the access period aP(1) the controller initiates a furtherswitching operation in step 314. The first communication stack St1 isinformed to stop access to the transmitter Tx at time t3_3. The secondcommunication stack St2 is informed to start the access to thetransmitter Tx at time t4_3.

During the following switching period swP, the controller CTRLdetermines in a step 316 the switching signal sw. According to a step318, upon receiving the switching signal sw the transmitter Tx changesits present first operating mode to the second operating mode in orderto use the second radio channel instead of the first radio channel inthe access period aP(2).

According to this example, multi-connectivity is achieved by using onlyone modem in the sense of the radio module RM. The shown time slotstructure comprises a fixed access period for each communication stackSt1 and St2. For example, a switch takes place every 2 ms between thefrequency bands of 2.4 GHz and 5 GHz. The usable time comprises theaccess periods aP(1) and aP(2) of the corresponding time slotsubtracting the RF switching period swP.

The first communication stack 1 compromises all required layers from theMAC layer upwards and is working as usual and transmits in the frequencyband 2.4 GHz. The first communication stack St1 has its own MAC address,IP address, etc. An ongoing transmission has to end before switching tothe second operating mode. At the end of the access period aP(1) thecurrent state of communication stack St1, e.g. the back-off timer,session timer, etc., is paused and continued in the next access periodaP(1). During the access period aP(2) the second communication stack St2accesses the transmitter Tx in order to transmit in the 5 GHz band basedon the status of the second communication stack St2. The communicationstacks St1 and St2 can be used for example by a multi-connectivityengine at the application APP to transmit duplicate data over twocommunication paths of different radio communications networks.

FIG. 4 schematically depicts a sequence diagram of a method to operatethe terminal T. The controller CTRL is configured to switch the at leastone parameter according to the first or second radio channel RCH1, RCH2in dependence on a received end of transmission indicator eot2, eot1,which indicates an end of a transmission via the second or first radiochannel RCH2, RCH1.

According to a step 402, the application APP determines payloads p1 andp2 and submits these to the corresponding communication stacks St1, St2.At the time t0_4 the second communication stack St2 starts access to thetransmitter Tx during the access period aP(2). During the access periodaP(2), the second communication stack St2 determines in a step 404 thatthe communication stack St2 will end its access to the transmitter Tx attime t1_4. During the switching period swP the controller CTRL schedulesvia a step 406 the selection of the first operating mode of thetransmitter Tx. Step 406 comprises that the first communication stackSt1 is informed that it has access to the transmitter Tx starting attime t2_4 to use the transmitter Tx. Step 406 comprises that thetransmitter Tx is informed via the switching signal sw to switch theoperation mode of the transmitter Tx in a step 408 to the firstoperating mode.

At a time t2_4 the first communication stack St1 starts access to thetransmitter Tx during the access period aP(1). During the access periodaP(1), the first communication stack St1 determines in a step 414 thatthe communication stack St1 will end its access to the transmitter Tx attime t3_4. During the switching period swP the controller CTRL schedulesvia a step 416 the selection of the second operating mode of thetransmitter Tx. Step 416 comprises that the second communication stackSt2 is informed that it has access to the transmitter Tx starting attime t4_4 to use the transmitter Tx. Step 416 comprises that thetransmitter Tx is informed via the switching signal sw to switch theoperation mode of the transmitter Tx in a step 418 to the secondoperating mode.

FIG. 5 schematically depicts a sequence diagram of a method to operatethe terminal T.

The receiver Rx is configured to receive at least one grant g1, g2 thatgrants the transmitter Tx to transmit data via the first or second radiochannel RCH1, RCH1. The controller CTRL is configured to switch to thefirst or second operating mode in dependence on the received grant g1,g2.

The controller CTRL is configured to operate the transmitter Tx totransmit a first scheduling request r1 during the first operating modetowards a scheduling entity N1 of the first radio communicationsnetwork.

The controller CTRL is configured to operate the transmitter Tx totransmit a second scheduling request r2 during the second operating modetowards a scheduling entity N2 of the second radio communicationsnetwork.

According to a step 502, the application APP determines payloads p1 andp2 and submits these to the corresponding communication stacks St1, St2.At the time t0_5 the second communication stack St2 starts accessing thetransmitter Tx during the access period aP(2). During the access periodaP(2), the second communication stack St2 has access to the transmitterTx. In an example not shown, the second communication stack St2 caninitiate a transmission of the second payload p2 to the network node N2of the second radio communication network. The controller CTRL schedulesin step 504 that the second communication stack St2 ends its access ofthe transmitter at time t1_5 and that the first communication stack St1starts accessing the transmitter Tx at time t2_5.

During the subsequent switching period swP, the controller CTRLinitiates in step 508 a switch of the second operating mode of thetransmitter Tx to the first operating mode. In step 510, the transmitterswitches to the first operating mode in dependence on the receivedswitching signal sw.

During the access period aP(2) in step 506 the controller CTRL or thesecond communication stack St2 (not shown) causes the transmitter Tx totransmit a scheduling request r2 towards the network node N2 that isconfigured as a scheduling entity for the second radio communicationnetwork. The network node N2 determines in step 511 the grant g2, whichis received by the receiver Rx of the radio module RM. The receiver Rxpasses the grant g2 to the controller CTRL. In step 512, the controllerCTRL informs in dependence on the grant g2 the first communication stackSt1 that it has to end access to the transmitter until time t3_5.

In the step 512, the controller CTRL informs in dependence on the grantg2 that the second communication stack St2 will gain access to thetransmitter Tx beginning with time t4_5. The grant g2 indicates a radioresources of the second radio channel in the access period aP(2) betweent4_5 and t5_5.

The controller CRTL starts its switching procedure at time t3_5. In step514, the controller CRTL determines the switching signal sw so that thetransmitter Tx changes its operating mode to the second operating modein step 516. According to the received grant g2, the secondcommunication stack St2 is able to transmit payload data p2 via thegranted radio resources of the second radio channel.

During the access period aP(2) between t2_5 and t3_5 the controller CTRLor (not shown) the first communication stack St1 initiates in step 520 agrant request r1 to be sent via the transmitter Tx towards the networknode N1 that acts as a scheduling entity for the first radiocommunication network. The network node N1 schedules the radio resourcesof the first radio channel and determines in step 522 a grant g1 that isreceived by the receiver Rx and handed over to the controller CTRL.

According to step 524, the controller CTRL informs the firstcommunication stack St1 that it can access the transmitter Tx startingwith time t6_5, and informs the second communication stack St2 that itsaccess to the transmitter Tx will end at time t5_5. The following steps508 and 510 depend on the determined time t5_5.

The provided method aligns the switching periods swP and the accessperiods aP(1) and aP(2) based on the scheduling decisions from thecentrally coordinated communication in the first and second radiocommunication network. In this case, both radio communication networksare centrally coordinated. For example, in case that both system arescheduled semi-persistent the controller CTRL will influence the networknodes N1 and N2 to schedule the respective radio resources such that thescheduled radio resources for both radio communication networks arescheduled non-overlapping in time. By doing so the switching period swPand the access periods aP(1) and aP (2) are adapted to the correspondingresource allocation and no radio resource according to the grants g1, g2is missed by the radio terminal T.

A further example of scheduling of the switching is given in thefollowing. In a system where IEEE 802.11 in HCCA mode is used, theContention Free Period (CFP), during which the HCCA controller CTRLmanages the channel access, and the Contention Period (CP), during whichthe channel is used by other nodes in DCF mode, switch periodically.HCCA is a centrally coordinated communication scheme in which a HybridCoordinator control the access to the medium. If both radiocommunication networks use the HCCA mode, the controller CTRL willinfluence the network nodes N1 and N2 such that the CFP periods of bothradio systems do not overlap in time and schedule the switching betweenthe two radio communication networks accordingly.

If only one radio communication network uses the HCCA and the otherradio communication network is using a distributed scheme, e.g., the802.11 DCF, the controller CTRL will schedule the switching according tothe CFP periods of the HCCA, radio communication network and let theother communication stack transmit in the remaining time slot with besteffort.

According to a further example not shown in its entirety, the controllerCTRL is configured to remain with the present operating mode or switchto the first or second operating mode in dependence on a transmissionpriority of data. The controller CTRL compares the transmissionpriorities of the MAC PDUs in the egress queues of the differentcommunication stacks St1 and St2. Therefore, if the controller CTRL alsoconsiders a higher transmission priority for MAC PDUs of the firstcommunication stack St1 in step 512, the controller CTRL will ignore inthe step 512 the grant g2 and remain with the first operating mode ofthe transmitter Tx as active.

Furthermore, in a mixed setup, where the medium access of the firstradio communication network is coordinated centrally and the mediumaccess of the second radio communication network is managed in adistributed manner, the switching times can be adjusted such that theygive priority to the resources of the first radio communication network.By doing so, at least the path over the first radio communicationsnetwork can predictably transmit packets whereas the second radiocommunications network is only transmitting with best effort. However,the access period for the first communication stack St1 is kept to aminimum, which leaves more time for the second communication stack St2to access the channel.

FIG. 6 schematically depicts a sequence diagram. The receiver Rx isconfigured to sense the first radio channel as free or busy.

The controller CTRL is configured to switch the transmitter Tx from thefirst operating mode to the second operating mode, if the first radiochannel RCH1 is sensed free, and to switch the transmitter Tx from thesecond operating mode to the first operating mode, if the first radiochannel RCH1 is sensed busy.

According to a step 602, the application APP determines payloads p1 andp2 and submits these to the corresponding communication stacks St1, St2.At the time t0_6 the controller CTRL informs in step 604 the secondcommunication stack St2 that it has access to the transmitter Txbeginning with time t1_6. In dependence on the received switching signalsw the transmitter Tx changes in step 606 its operating state to thesecond operating state.

The receiver Rx sense the first radio channel RCH1 as busy at time t2_6and starts in step 608 to change the operating state of the transmitterTx to the first operating state. The transmitter Tx changes itsoperating state to the first operating state in step 610. The secondcommunication stack St2 is informed to stop access to the transmitterTx. The first communication stack St2 is informed that access to thetransmitter Tx is provided starting with time t3_6.

As soon as the receiver Rx senses the first channel RCH1 as free, thecontroller CTRL initiates in step 612 a change of the operating state ofthe transmitter Tx to the second operating state in step 614.

The second communication stack St2 starts accessing the transmitter Txduring the access period aP(2). During the access period aP(2), thesecond communication stack St2 has access to the transmitter Tx. In anexample not shown, the second communication stack St2 can initiate atransmission of the second payload p2 to the network node N2 of thesecond radio communication network. The controller CTRL schedules instep 504 that the second communication stack St2 ends its access of thetransmitter at time t1_5 and that the first communication stack St1starts accessing the transmitter Tx at time t2_5.

According to this exemplary setup, transmissions take place according toa non-coordinated scheme in which radio terminals T in the 3.7 GHz actas primary users and those radio terminals T in the Wi-Fi band assecondary users. Therefore, Wi-Fi users can start to transmit only ifthere is no 3.7 GHz transmission. That means, the controller CTRLmonitors the at least the first radio channel RCH1 in order to detectthe existence of a potential transmission. As long as the transmissionin 3.7 GHz/the first radio channel RCH1 is paused, the Wi-Fi users wouldtake this opportunity to transmit an unknown quantity of data (burst)depending of the time allocated and have to vacate as soon as 3.7 GHztransmissions follow, which means that the first radio channel RCH1 issensed busy. In other words, Wi-Fi users take opportunity of idleperiods for transmission of data on the second radio channel RCH2. Thissetup takes into account conventional Wi-Fi users using CSMA/CA as wellas users in a tuned Wi-Fi system without a channel access mechanism.

1. A radio module (RM) for a radio terminal (T), the radio module (RM)comprising: a transmitter (Tx) configured to transmit data within a timeperiod either on a first radio channel (RCH1) of a first radiocommunications network according to a first operating mode or on asecond radio channel (RCH2) of a second radio communications networkaccording to a second operating mode; and a controller (CTRL) configuredto schedule a selection of one of the operating modes of the transmitter(Tx), wherein the selection comprises switching of at least oneparameter of the transmitter (Tx) according to the selected operatingmode.
 2. The radio module (RM) according to claim 1, wherein thetransmitter (Tx) is configured to encapsulate a received first type MACPDU into a first type PHY PDU, to map the first type PHY PDU to betransmitted on at least one first subcarrier and to subsequentlyup-convert to a first radio frequency higher than the at least one firstsubcarrier, and wherein the transmitter (Tx) is configured toencapsulate a received second type MAC PDU into a second type PHY PDU,to map the second type PHY PDU to be transmitted on at least one secondsubcarrier and to subsequently up-convert to a second radio frequencyhigher than the at least one second subcarrier.
 3. The radio module (RM)according to claim 1, wherein the controller (CTRL) is configured toswitch the at least one parameter according to the first or second radiochannel (RCH1; RCH2) in dependence on a pre-determined switching patternwhich comprises fixed access periods (ap) for the transmitter (Tx). 4.The radio module (RM) according to claim 1, wherein the controller(CTRL) is configured to switch the at least one parameter according tothe first or second radio channel (RCH1; RCH2) in dependence on areceived end of transmission indicator (eot2; eot1), which indicates anend of a transmission via the second or first radio channel (RCH2;RCH1).
 5. The radio module (RM) according to claim 1, wherein the radiomodule (RM) comprises: a receiver (Rx) configured to receive at leastone grant (g1; g2) to transmit data via the first or second radiochannel (RCH1; RCH1); and wherein the controller (CTRL) is configured toswitch to the first or second operating mode in dependence on thereceived grant (g1; g2)
 6. The radio module (RM) according to claim 5,wherein the controller (CTRL) is configured to operate the transmitter(Tx) to transmit a first scheduling request (r1) during the firstoperating mode towards a scheduling entity (N1) of the first radiocommunications network.
 7. The radio module (RM) according to claim 5,wherein the controller (CTRL) is configured to operate the transmitter(Tx) to transmit a second scheduling request (r2) during the secondoperating mode towards a scheduling entity (N2) of the second radiocommunications network.
 8. The radio module (RM) according to claim 1,wherein the controller (CTRL) is configured to remain with the presentoperating mode or switch to the first or second operating mode independence on a transmission priority (p1; p2) of data.
 9. The radiomodule (RM) according to claim 1, wherein the radio module (RM)comprises a receiver (Rx) configured to sense the first or second radiochannel (RCH1; RCH2) as free or busy; and wherein the controller (CTRL)configured to switch the transmitter (Tx) from the first operating modeto the second operating mode, if the first radio channel (RCH1) issensed busy, and to switch the transmitter (Tx) from the secondoperating mode to the first operating mode, if the second radio channel(RCH2) is sensed busy.
 10. The radio module (RM) according to claim 1,wherein the radio module (RM) comprises: a receiver (Rx) configured toreceive data within a time period either on the first radio channel(RCH1) of the first radio communications network according to the firstoperating mode or on the second radio channel (RCH2) of the second radiocommunications network according to the second operating mode.
 11. Amethod to operate a radio module (RM), the method comprising:transmitting data within a time period either on a first radio channel(RCH1) of a first radio communications network according to a firstoperating mode or on a second radio channel (RCH2) of a second radiocommunications network according to a second operating mode; andscheduling a selection of one of the operating modes of the transmitter(Tx), wherein the selection comprises switching of at least oneparameter of the transmitter (Tx) according to the selected operatingmode.
 12. A radio terminal (T) for at least two radio communicationnetworks, wherein the radio terminal (T) comprises a transmitter (Tx)configured to transmit data within a time period either on a first radiochannel (RCH1) of a first radio communications network according to afirst operating mode or on a second radio channel (RCH2) of a secondradio communications network according to a second operating mode; and acontroller (CTRL) configured to schedule a selection of one of theoperating modes of the transmitter (Tx), wherein the selection comprisesswitching of at least one parameter of the transmitter (Tx) according tothe selected operating mode.
 13. The radio terminal (T) according toclaim 13, wherein the radio terminal (T) comprises at least oneprocessor, at least one memory with computer program code, and at leastone antenna, the computer program code being configured to interact withthe at least one processor, the at least one antenna, and the at leastone radio module (RM) to cause the radio terminal (T) to determine a/thefirst type MAC PDU in dependence on a first payload and provide thefirst type MAC PDU to the transmitter (Tx); and determine a/the secondtype MAC PDU in dependence on a second payload and provide the secondtype MAC PDU to the transmitter (Tx).